Polyurethane-containing building materials

ABSTRACT

Concrete containing polyurethane is provided and construction elements comprising such concrete. Methods for the preparation of polyurethane powder for inclusion in such concrete and for the formation of construction elements comprising such concrete are also provided.

TECHNICAL FIELD

This invention relates to building materials, particularly concretescontaining polyurethane, and panels comprising such building materials.The invention also relates to methods or preparing such buildingmaterials.

BACKGROUND ART

Panel boards are by used during the construction of buildings to formthe surface of walls, floors and ceilings. Such panels generallycomprise a core material sandwiched between two layers of coveringmaterial. Plasterboard is a commonly used example of a panel board,comprising hardened plaster niched between two layers of card. Panelboards may also have plywood cores. In parts of a building which comeinto contact with water, for example bathrooms, panel boards may be usedwhich could typically comprise gypsum-based plasterboard or acement-based board sandwiched between two layers of mesh.

Several manufacturers have developed the construction of these basicpanel board products using materials other than concrete to make themmore lightweight than boards of traditional construction. For example,U.S. Pat. No. 0,082,365 discloses a lightweight board comprising apolyisocyanurate or polyurethane foam core with lower and upper surfacesand filler material such as wood chips within the foam core. The boardis intended primarily for use as an insulator in roof construction.

Marmox® (Marmox (UK) Ltd, Rochester, Kent, UK) is a lightweightunfinished board product which comprises extruded polystyrene with afibreglass reinforced face set in a cement polymer adhesive. It issufficiently strong to be suitable for the construction of walls andfloors. The surface will accept both plaster and paint, or tiles toprovide a finished surface. Marmox boards are also waterproof andtherefore suitable for use in moist areas such as bathrooms.

Other panels include Aquapanel® which is a building board composed ofcement and reinforced with glass fibre mesh. Respatex® and Wetwall™ areboth board products comprising a plywood core and laminate faces,suitable for wall cladding only.

Polyurethane (PUR) is an artificial material which is used in rubberform, in sealants and in a rigid foam form as insulation for, amongstother things, refrigeration units. The blowing agents used to generatethe foam structure in PUR foam have traditionally beenchlorofluorocarbons (CFCs). The environmental consequences of therelease of CFCs when a refrigeration unit is broken up at the end of itslife are well known. Less widely publicised, however, arm theconsequences of the disposal of the remaining PUR foam waste, whichoften ends up in landfill sites. It is preferable to recycle such wastein order to minimise the volume of such material which ends up inlandfills.

DISCLOSURE OF INVENTION

According to a first aspect of the invention there is provided concretecomprising PUR. The concrete may comprise a binding agent, water andPUR. The PUR may preferably be PUR foam. The binding agent may be cementor gypsum. Examples of suitable cement include, but are not restrictedto, Ordinary Portland Cement, Rapid Hardening Port Cement, SulphateResisting Portland Cement and other Portland Cements containing variousadditives. Examples of suitable gypsum-based products include, but arenot restricted to, Gyproc®, Gyplite® and Blue Hawk®. In a preferredembodiment, the concrete may further comprise at least one bulkingagent, waterproofing agent and/or flowing agent. The bulking agent maybe limestone dust or silica sand. The waterproofing agent may be Xypex®admix C-1000 (Xypex Chemical Corporation, Canada) or Hydrophobe™ (WRGrace & Co., Cambridge, United Kingdom). The flowing agent may be an airentrainer, for example, Airalon™ (WR Grace & Co.).

Preferably, the concrete according to the invention may comprise: Cement240-450 kg/m³ PUR 200-395 kg/m³ Bulking agent  0-300 kg/m³ Waterproofingagent  0.1-0.3% w/w cement (Hydrophobe) Flowing agent 0.03-0.06% w/wcement (Airalon) Water 160-450 l/m³

Most preferably the concrete according to the invention may comprise:Cement approx. 375 kg/m³ PUR approx. 250 kg/m³ Bulking agent approx. 250kg/m³ Waterproofing agent  0.1-0.3% w/w cement (Hydrophobe) Flowingagent 0.03-0.06% w/w cement (Airalon) Water approx. 200 l/m³

Alternatively, the concrete according to the invention may comprise:Cement approx. 300 kg/m³ PUR approx. 327 kg/m³ Waterproofing agent 0.1-0.3% w/w cement (Hydrophobe) Flowing agent 0.03-0.06% w/w cement(Airalon) Water approx. 373 l/m³

There is further provided a panel board comprising concrete according tothe first aspect of the invention.

It is an advantage of the current invention that, as the result of thereplacement of at least some of the usual sand bulking agent with PURfoam, the resistant concrete may be used to form panel boards which arelightweight compared with traditional concrete panel boards. ThePUR-containing concrete panel boards are strong enough to be used in theconstruction of walls and floors and also can be waterproof such thatthey can be used to form walls in moist areas such as bathrooms.

According to a second aspect of the invention, there is provided amethod for preparing dried expanded PUR foam for use in the preparationof concrete, comprising:

-   -   a) soaking granulated PUR foam in water for a period of time        sufficient to allow the PUR to expand,    -   b) separating the PUR from the water; and    -   c) drying the PUR.

It is a further advantage of this aspect of the current invention thatthe granulated PUR foam is pre-expanded by the soaking treatment, henceallowing it to stabilise, eliminating the risk of further expansion onaddition of the remaining water and cement during mixing ofPUR-containing concrete.

The water may be between pH 6 and pH 9. Preferably the water may bepotable. The granulated PUR foam may be soaked in water for betweenabout ten minutes and about two days, preferably for between about 1.5and about 2.5 hours, most preferably for about 2 hours. The expanded PURmay be dried by standing in air or by forcing air past it. The air maybe heated. The expanded PUR may be dried under pressure.

The method according to the second aspect of the invention may furthercomprise a step to determine the water content of the dried expandedPUR.

The granulated PUR foam used in the invention may comprise recycled PURfoam. The granulated PUR foam may be previously prepared from PUR foamchunks also containing impurities such as aluminium and/or plasticsmaterial. The PUR foam chunks may be granulated using a granulator,using high pressure water jets pressurised at between 10.35 and 48.25MPa, preferably 20.7 MPa, or by adding water and mixing in a high shearmixer. The mixer may preferably operate at between 2000 and 6000 rpm,most preferably at about 4000 rpm. The impurities may be removed bypassing the granulated PUR through a mesh screen, preferably of between75 μm and 4750 μm gauge, most preferably of about 2360 μm gauge.

There is further provided dried expanded PUR obtainable by a methodaccording to the second aspect of the invention.

There is also provided a method for preparing a building material whichcomprises mixing a binding agent, water and dried expanded PURobtainable by a method according to the second aspect of the invention,and building materials so produced. The components of the buildingmaterial may be mixed in a high shear mixer. The binding agent may becement or gypsum. The method may further comprise mixing at least onebulking agent, waterproofing agent and/or flowing agent with the othercomponents of the mix. The bulking agent may be limestone dust or silicasand. The waterproofing agent may be Xypex admix C-1000. The flowingagent may be an air entrainer or a plasticiser. The components of themix may be present in the quantities: Cement 240-450 kg/m³ PUR 200-395kg/m³ Bulking agent  0-300 kg/m³ Waterproofing agent  0.1-0.3% w/wcement (Hydrophobe) Flowing agent 0.03-0.06% w/w cement (Airalon) Water160-450 l/m³

The components of the mix may preferably be present in the quantities:Cement approx. 375 kg/m³ PUR approx. 250 kg/m³ Bulking agent approx. 250kg/m³ Waterproofing agent  0.1-0.3% w/w cement (Hydrophobe) Flowingagent 0.03-0.06% w/w cement (Airalon) Water approx. 200 l/m³

Alternatively, the components of the mix may be present in thequantities: Cement approx. 300 kg/m³ PUR approx. 327 kg/m³ Waterproofingagent  0.1-0.3% w/w cement (Hydrophobe) Flowing agent 0.03-0.06% w/wcement (Airalon) Water approx. 373 l/m³

According to a further aspect of the invention, there is provided amethod of preparing a construction element comprising:

-   -   a) preparing a mould sized to reflect the intended dimensions of        the construction element;    -   b) introducing a PUR building material comprising dried expanded        PUR obtinable by a method according to the second aspect of the        invention into the mould;    -   c) curing the so formed construction element; and    -   d) separating the mould and construction element.

Typically the construction element will be a panel board. Otherconstruction elements include for example beams, spars and joists.

Preparing the mould may comprise laying glass fibre matting in the baseof the mould and covering the matting with a layer of cementatiousgrout. The glass fibre matting may preferably be alkaline resistant. Thecementatious grout layers may be 1-4 mm thick, preferably 1.5-2 mmthick, most preferably about 2 mm thick. The cementatious grout may havea plastic density of between 2000 and 2300 kg/m², preferably about 2180kg/m² and have a cement content of between 400 and 500 kg/m³. The glassfibre matting may extend outside the mould. Following the pouring of thePUR building material into the mould, the glass fibre matting whichextends outside the mould may be folded onto the non-mould facingsurface of the PUR building material.

Preparing the mould may alternatively comprise spraying and rolling alayer of glass reinforced cement (GRC) into the base of the mould. Thesprayed and rolled layer of GRC may be 14 mm thick, preferably 1.5-2 mmthick, most preferably about 2 mm thick. Glass fibre may be present inthe GRC at about 2% w/w cementatious grout. Cementatious grout presentin the GRC may have a plastic density of between 2000 and 2300 kg/m²,preferably about 2180 kg/m² and a cement content of between 400 and 500kg/m³. The GRC may be sprayed and rolled onto at least one ended mouldpiece and left for a period of time sufficient to allow the mix to setto form at least one GRC layer. Following the pouring of the PURbuilding material into the mould, the or each GRC layer may be foldedonto the non-mould facing surface of the PUR building material.

After the PUR building material has been poured into the mould, themould may be agitated to ensure uniform distribution within the mould ofthe PUR building material. The mould may be placed an a vibrating tableto enable the agitation.

The method of preparing a construction element may further comprise:

-   -   a) the laying of the glass fibre matting over the non-mould        facing surface of the poured PUR building material; and    -   b) the addition of a layer of cementatious grout over the top        surface of the GRC matting.

The method may yet further comprise the trowel finishing of thecementatious grout layer. The glass fibre matting may preferably bealkaline resistant. The cementatious grout layer may be 1.5-2 mm thick.The cementatious grout may have a plastic density of between 2000 and2300 kg/m², preferably about 2180 kg/m² and a cement content of between400 and 500 kg/m³.

The method of preparing a construction element may alteratively furthercomprise the spraying and rolling of a layer of GRC onto the non-mouldfacing surface of the poured PUR building material. The method may yetfurther comprise the trowel finishing of the GRC layer. The sprayed androlled layer of GRC may be 1.5-2 mm thick. Glass fibre may be present inthe GRC at about 2% w/w cement grout. Cementatious grout present in theGRC may have a plastic density of between 2000 and 2300 kg/m²,preferably about 2180 kg/m² and a cement content of between 400 and 500kg/m³. The curing in the method of preparing a construction element maybe air-curing for between 10 and 24 hours, preferably about 12 hours.Alternatively, the curing may be accelerated by curing in a mist chamberfor between 6 and 15 hours, preferably about 8 hours.

There is further provided a construction element for use in constructionobtainable by a method according to the invention.

There is further provided a building element comprising at least twoconstruction elements which comprise dried expanded PUR obtainable by amethod according to the second aspect of the invention. Typically, eachconstruction element will be a panel board. The construction elementsmay be fixed together to maintain a void between each constructionelement. One or more voids may be filled with self compacting concrete,preferably reinforced concrete. One or more voids may be filled with airentrained concrete. The air entrained concrete may comprise PUR.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will now be described by way of exampleonly and with reference to the following FIGS. 1-8 in which:

FIG. 1 is a flow digram showing the stages in a method of producinggrannulated PUR foam from recycled PUR foam briquettes;

FIG. 2 is a flow diagram showing the stages in a method of producingdried expanded PUR;

FIG. 3 shows a mould with glass fibre matting laid in the base andoverlaid with a layer of cementatious grout;

FIG. 4 is a cross-section along the line A-A;

FIG. 5 shows a mould comprising extended mould pieces, with glassreinforced cement sprayed and rolled into the mould and onto the sideextensions;

FIG. 6 shows a cross-section along the line B-B;

FIG. 7 is a flow diagram showing the stages in a method of producing apanel board constructed from PUR-containing building material; and

FIG. 8 is a cross-section through a two-void building elementconstructed using PUR-containing panel boards.

MODES OF CARRYING OUT THE INVENTION

1. Preparing Granulated PUR Foam from PUR Foam Briquettes

PUR foam briquettes are produced when, for example, refrigeration unitscontaining PUR foam are dismantled. The briquettes are formed fromrecycled PUR foam and contain impurities, for example, plastic andaluminium fragments. A method for converting PUR briquettes into PURsuitable for use in the methods and materials according to the inventionis outlined in FIG. 1.

The briquettes may first be broken down into granules using agranulator, such as a Getecha model RS3009 (Getecha UK Ltd, Warminster,Wiltshire, United Kingdom). Alternatively, they may be granulated usinghigh pressure water jets, operating at a preferred pressure of 20.7 MPa.In a further alternative, the briquettes may be granulated by mixingwith water and shredding in a high shear mixer, for example a GRC125(2-speed) mixer (Power Sprays Ltd, Bristol, United Kingdom), typicallyoperating at 4000 rpm.

The PUR granules, dry or wet depending on the method of granulation, arethen passed through a screen, typically about 2360 μm gauge. This screenremoves impurities such as pieces of plastic or aluminium, allowingcleaned granulated PUR to pass through.

2. Preparation of PUR for Use in Building Materials.

Cleaned PUR prepared as described in Example 1 above or by otherpreparation means, or alternatively newly manufactured PUR foam, isprepared for use in building materials by a method which is summarisedin FIG. 2. The granulated PUR foam is soaked in potable water for about2 hours. This period of time allows the PUR to fully expand to form PURwhich will typically float to the surface of the water.

The expanded PUR is skimmed from the surface of the water. It is thendried, either by air drying or by drying under pressure. The expandedPUR may be air dried by leaving it to stand in air, or by passing airover it. The air may be heated or be at ambient temperature.Alternatively, the expanded PUR may be pressure dried by squeezing thePUR and draining the water away.

The dried expanded PUR is then weighed and analysed for remaining watercontent. This allows the calculation of he correct volume of water to beadded when the dried expanded PUR is used in the mixing of buildingmaterials. This weighing and analysing step may be omitted once atypical water content, resulting from a given set of preparationconditions, is known.

3. Mixing of Building Materials Containing Dried Expanded PUR

Building materials containing dried expanded PUR may be cement based orgypsum based. Typical quantities of the components of such buildingmaterials are shown below, in Table 1: TABLE 1 quantities of componentsof PUR-containing building material Finished relative density 0.97 0.6Cement 375 kg/m³ 300 kg/m³ PUR 250 kg/m³ 327 kg/m³ Limestone dust/ 250kg/m³ 0 silica sand Waterproofing agent 0.1-0.3% 0.1-0.3% (Hydrophobe)w/w cement w/w cement Flowing agent (Airalon) 0.03-0.06% 0.03-0.06% w/wcement w/w cement Water 200 l/m³ 373 l/m³

The components of such building materials are mixed in a high-shearmixer, for example a GRC125 (2-speed) mixer as mentioned in Example 1above.

4. Preparation of a Mould for the Production of PUR-Containing PanelBoards

A mould, sized to reflect the finished board dimensions, is prepared inone of the two following ways:

-   -   a) As shown in FIGS. 3 and 4, a sheet of alkaline-resistant        glass fibre matting (1) is laid in a mould (5), extending        outside the mould on two opposite sides (10, 15) by        approximately 70-100 mm. The matting lining the base (20) and        sides (25, 30) of the mould is covered with an approximately 2        mm layer of cementatious grout (35), typically of plastic        density of about 2180 kg/m² and cement content of between 400        and 500 kg/m³.    -   b) As shown in FIGS. 5 and 6, a mould (37) has extended mould        pieces (40, 45) on two opposite sides (50, 55). A layer of        glass-reinforced cement (GRC, glass fibre pre-mixed with        cementatious grout) (60) is sprayed and rolled into the mould,        also spraying the upper surfaces of the extended mould pieces        with GRC up to 70-100 mm from the sides of the mould (50, 55).        The glass fibre is typically present at about 2% w/w        cementatious grout. The cementatious grout typically is of        plastic density of about 2180 kg/m² and cement content of        between 400 and 500 kg/m³.

The moulds may be prepared on a viewing table.

5. Preparation of PUR-Containing Panel Boards in Prepared Moulds.

The preparation of PUR-containing panel boards is outlined in FIG. 7. Acement-based PUR-containing building material, of a compositiondescribed in Example 3 above, is introduced into a mould prepared asdescribed in Example 4 above. The mould is then agitated to settle thePUR-containing building material and to remove any air bubbles. If themould has been prepared on a vibrating table, the table may be vibratedto facilitate this agitation.

If the mould was prepared as described in Example 4a above, the lowerlayer of glass fibre matting which overlays the sides of the mould arefolded in to make contact with the non-mould facing surface of thePUR-containing building material. A further layer of glass fibre mattingis layered onto the non-mould fitting surface of the PUR-containingbuilding material and the folded in lower layer of glass fibre matting.The top surface of the glass fibre matting is covered with anapproximately 2 mm layer of cementatious grout, typically of plasticdensity of about 2180 kg/m² and cement content of between 400 and 500kg/m³. The top surface of the cement grout is trowel finished to formthe panel board's outer surface.

If the mould was prepared as described in Example 4b above, the lowerGRC layer which was sprayed onto the extended mould pieces is folded into make contact with the non-mould facing surface of the PUR-containingbuilding material. A further layer of GRC is sprayed and rolled onto thenon-mould facing surface of the PUR-containing building material and thefolded in lower GRC layer. The glass fibre is typically present at about2% w/w cementatious grout. The cementatious grout typically is ofplastic density of about 2180 kg/m² and cement content of between 400and 500 kg/m². The top surface of the GRC layer is trowel finished toform the panel board's outer layer.

The formed panel boards are next left to cure. Curing may be facilitatedby air curing for between 10 and 24 hours, preferably for about 12hours, or by mist chamber curing for between 6 and 15 hours, preferablyabout 8 hours, until the board is suitable for striking from the mould.Care should be taken, in particular in the case of air curing, to takeappropriate steps to prevent surface crazing and cracking caused by highambient temperature drying.

When the formed panel board has been suitably cured it is struck fromthe mould. The finished panel board product is suitable for variousbuilding applications. A panel board made using PUR-containing buildingmaterial of for example, 0.85 final relative density is suitable for usein wall applications. A panel board made using PUR-containing buildingmaterial of, for example, 0.97 final relative density is suitable foruse in floor applications. By way of comparison, Aquapanel® has a finalrelative density of about 1.2.

6. Two-Void Building Element Constructed Using PUR-Containing PanelBoards

A two-void building element is constructed as shown in FIG. 8. ThreePUR-containing panel boards (65) are fixed together by suitable ties,for example Rapid Bar Ties (RMD Kwikform, Walsall, UK), so as tomaintain a void between each board.

The outer “structural” void (70) is filled with self compacting concretewhich may be reinforced concrete. The inner “insulation” void (75) isfilled with a lightweight air entrained concrete which may also containPUR. The wall resulting from such a construction has good thermalinsulation properties with U-values of 0.45 W/m²K or better.

INDUSTRIAL APPLICABILITY

Products and methods in accordance with the invention can be used inindustry, in particular, though not exclusively, in the constructionindustry.

1-15. (canceled) 16: A method for preparing dried expanded PUR for usein the preparation of concrete, comprising: a) soaking granulated PURfoam in water for a period of time sufficient to allow the PUR toexpand; b) separating the PUR from the water, and c) drying the PUR. 17:A method according to claim 16, wherein the water is between pH6 andpH9. 18: A method according to claim 17, wherein the water is potable.19: A method according to claim 16, 17 or 18 wherein the PUR is soakedin water for between ten minutes and two days. 20: A method according toclaim 19 wherein the PUR is soaked in water for between 1.5 and 2.5hours. 21: A method according to claim 20 wherein the PUR is soaked inwater for about 2 hours. 22: A method according to claim 16 wherein theexpanded PUR is dried by standing in air. 23: A method according toclaim 16 wherein the expanded PUR is dried by forcing air past it. 24: Amethod according to claim 22 or 23 wherein the air is heated. 25: Amethod according to claim 16 wherein the expanded PUR is dried underpressure. 26: A method according to claim 16 further comprising a stepto determine the water content of the dried PUR. 27: A method accordingto claim 16 wherein the PUR comprises recycled PUR foam. 28: A methodaccording to claim 27 wherein the PUR is previously prepared from PURfoam chunks also containing impurities such as aluminium and/or otherplastics material. 29: A method according to claim 28 wherein the PURfoam chunks are granulated and the impurities removed. 30: A methodaccording to claim 29 wherein the PUR foam chunks are granulated using agranulator. 31: A method according to claim 29 wherein the PUR foamchunks are granulated using high pressure water jets. 32: A methodaccording to claim 31 wherein the water jets are pressurised at between10.35 and 48.25 MPa. 33: A method according to claim 32 wherein thewater jets are pressurised at about 20.7 MPa. 34: A method according toclaim 29 wherein the chunks are granulated by adding water and mixing ina high shear mixer. 35: A method according to claim 34 wherein the mixeroperates at between 2000 and 6000 rpm. 36: A method according to claim35 wherein the mixer operates at about 4000 rpm. 37: A method accordingto claim 29 in which the impurities are removed by passing thegranulated PUR foam through a mesh screen. 38: A method according toclaim 37 in which the mesh screen is of between 75 μm and 4750 μm gauge.39: A method according to claim 38 in which the mesh screen is of about2360 μm gauge. 40: Dried expanded PUR obtainable by a method of claim16. 41-102. (canceled)